\documentclass{standalone}
\usepackage{tikz,ctex}
\usetikzlibrary{patterns}
\begin{document}
\footnotesize
  \begin{tikzpicture}[>=stealth,scale=0.6]
    \draw[thick](140:0.2)--(0,0)--++(-130:1.65)arc(140:230:0.3)--++(-40:0.4)arc(-130:-40:0.3)--++(50:1.65)--++(-40:0.2)--++(-120:0.5620)arc(150:270:1.0)--++(0.2,0)--++(0,-0.2)--++(-4.7441,0)--++(0,0.2)--cycle;
    \draw[thin,<->](-130:0.5)--++(-40:1.0)node[midway,sloped,above]{$b$};
    \draw[thin,<->](-3.0398,-3.5)--(1.7043,-3.5)node[midway,sloped,above]{$L$};
    \draw[thin,<->](2.3,-2.9581)--(2.3,0.1286)node[midway,sloped,above]{$H$};
    \draw[thin](0,0.1286)--(2.4,0.1286)(1.8,-2.9581)--(2.4,-2.9581);
    \draw[thin](-3.0398,-3.0)--(-3.0398,-3.6)(1.7043,-3.0)--(1.7043,-3.6);
  \end{tikzpicture}
\end{document}